Communication network, path setting method, network management system and node

ABSTRACT

A hierarchized path setting system in a communication network efficiently contains lower order paths in higher order path. The communication network has a plurality of nodes capable to perform switching process and demultiplexing process not only for lower order paths in a predetermined hierarchical level among hierarchized paths but also for higher order paths in a hierarchical level higher than the predetermined hierarchical level, and a plurality of links connecting these nodes. The system is responsive to a new path setting demand for setting the lower order path, for setting the lower order path in the higher order path when a single higher order path is set from a predetermined transmitter node group, in which a transmitter node of the lower order path belongs, to a predetermined receiver node group including a receiver node.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

Japan Priority Application 2001-237325, filed Aug. 6, 2001 including thespecification, drawings, claims and abstract, is incorporated herein byreference in its entirety. This application is a Divisional of U.S.application Ser. No. 10/211,332, filed Aug. 5, 2002, incorporated hereinby reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a communication network, apath setting method, a network management system and a node. Moreparticularly, the invention relates to a hierarchical path settingsystem in a communication network, in which paths having mutuallydifferent granularities are present in admixing manner.

2. Description of the Related Art

Currently, in communication network, attempt is made for establishingpaths having variety of granularities. For example, in an internet draft“draft-ietf-mpls-generalized-signaling-04.txt” (reference 1) of IETF(Internet Engineering Task Force), there has been proposed to establishATM (asynchronous Transfer Mode) path, VP/VC (Virtual Pass/VirtualChannel) path, SONET (Synchronous Optical Network)/SDH (SynchronousDigital Hierarchy) path, wavelength/waveband path, fiber path and soforth.

In the network containing a plurality of paths having mutually differentgranularities, the paths have conventionally been hierarchized pergranularities, lower order paths aggregated per sub-networks are set viahigher order paths. Here, the lower order path represents a path havingsmaller granularity, and the higher order path represents a path havinggreater granularity.

It becomes possible to switch the paths having smaller granularity setin the same route with the paths of greater granularity in multiplexingmanner by hierarchizing the paths to permit advantageously reduce a sizeof cross connect. On the other hand, the user may demand setting ofpaths of variety of granularities, such as 155 Mbit/s, . . . 2.g Gbit/s,10 Gbit/s and so forth, adapting to application.

The network having hierarchical has been disclosed in Suemura et al.,“Control of Hierarchical Paths in Optical Network,” PNI2000-37, theInstitute of Electronics Information and Communication Engineers,Japan,(reference 2), for example.

As one prior art, general network construction shown in the reference 1is illustrated in FIG. 12. The network consisted of optical networkdevices 102-1 to 102-16 having wavelength path is divided into aplurality of sub-networks 100-1 to 100-4 depending upon geographicalinformation, convenience in management or the like. These plurality ofsub-networks are connected to by optical network devices 101-1 to 101-6handling waveband path, one or more of which is provided in eachsub-network. As set forth above, the network handling the wavelengthpaths and the network handling the waveband path are hierarchized.

In such network, the optical paths are classified to paths set in thesub-network and paths set bridging sub-net works. Paths set from theoptical network devices 102-9 to 102-12 are established only bywavelength paths in the sub-network via the optical network device102-11. On the other hand, the path set from the optical network device102-1 to 102-16 is established by the wavelength paths in thesub-network and the waveband paths between the sub-networks via theoptical network devices 102-2, 101-1, 101-5, 101-3 and 102-14.

The reference 2 as the second prior art also discloses setting ofhierarchized path without dividing the network into sub-networks.Amongst, all nodes forming the network have construction for switchingthe wavelength paths and the waveband paths. In such network, when asetting demand of the wavelength path is given, a method deriving theshortest route to a receiver node by using CSPF (Constraint ShortestPath Fast) algorithm which calculates a routing path in consideration ofonly links having vacant wavelength and setting the wavelength pathsalong the calculated path, is repeated. When a number of the wavelengthpaths along certain route reaches a number to form the waveband path,aggregate of the wavelength paths is switched into the waveband path. Inthe foregoing procedure, hierarchized path is established by thewavelength paths and the waveband paths.

A first problem encountered in the first prior art is to waste networkresource upon occurrence of demand not matching with traffic patternsused in designing since the sub-networks are preliminarily designed infixed manner. For example, when one demand for lower order path betweenthe sub-networks is present, remaining bands are wasted within thehigher order path connecting between the sub-networks.

A second problem encountered in the first prior art is that failure ofthe node handling the higher order paths influences for all of thenetworks. Since the sub-networks are preliminarily designed in fixedmanner, the nodes handling the higher order paths are determined insimilar manner. Therefore, when failure is caused in the node handlingthe higher order paths, the path bridging between the sub-networkscannot be set since the higher order path cannot be set.

A problem in the second prior art is incapability of efficientlymultiplexing the lower order paths into the higher order path. While thesecond prior art can solve the second problem in the first prior art, itis not possible to intentionally aggregate lower order paths in the sameroute to switch into the higher order path. As a result, since thehigher order path cannot be established efficiently, advantage ofhierarchizing of the path can be degraded.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a hierarchized pathsetting system in a communication network to efficiently contain lowerorder paths in higher order path.

According to the first aspect of the present invention, a communicationnetwork comprises:

a plurality of nodes capable to perform switching process anddemultiplexing process not only for lower order paths in a predeterminedhierarchical level among hierarchized paths but also for higher orderpaths in a hierarchical level higher than the predetermined hierarchicallevel;

a plurality of links connecting these nodes; and

path setting control means responsive to a new path setting demand forsetting the lower order path, for setting the lower order path in thehigher order path when a single higher order path is set from apredetermined transmitter node group, in which a transmitter node of thelower order path belongs, to a predetermined receiver node groupincluding a receiver node.

According to the second aspect of the present invention, a communicationnetwork comprises:

a plurality of nodes capable to perform switching process anddemultiplexing process not only for lower order paths in a predeterminedhierarchical level among hierarchized paths but also for higher orderpaths in a hierarchical level higher than the predetermined hierarchicallevel;

a plurality of links connecting these nodes; and

path setting control means responsive to a new path setting demand forsetting the lower order path, the path setting control means setting thehigher order path between the transmitter node group consisted of nodesreachable from the transmitter node via the higher order path and thereceiver node when the single higher order path is not set between thetransmitter node of the lower order path and the receiver node, andsetting the lower order path via the set higher order path and the nodecontaining in the transmitter node group.

According to the third aspect of the present invention, a communicationnetwork comprises:

a plurality of nodes capable to perform switching process anddemultiplexing process not only for lower order paths in a predeterminedhierarchical level among hierarchized paths but also for higher orderpaths in a hierarchical level higher than the predetermined hierarchicallevel;

a plurality of links connecting these nodes; and

path setting control means responsive to a new path setting demand forsetting the lower order path, the path setting control means setting thehigher order path between the transmitter node group consisted of thenodes reachable from the transmitter node via the higher order path andthe receiver node group consisted of the nodes reachable from thereceiver node when the single higher order path is not set between thetransmitter node of the lower order path and the receiver node, andsetting the lower order path via the set higher order path and the nodecontaining in the transmitter node group and the receiver node group.

According to the fourth aspect of the present invention, a communicationnetwork comprises:

a plurality of nodes capable to perform switching process anddemultiplexing process not only for lower order paths in a predeterminedhierarchical level among hierarchized paths but also for higher orderpaths in a hierarchical level higher than the predetermined hierarchicallevel;

a plurality of links connecting these nodes; and

path setting control means responsive to a new path setting demand forsetting the lower order path, the path setting control means setting thehigher order path between the transmitter node and the receiver nodegroup consisted of the nodes reachable from the receiver node when thesingle higher order path is not set between the transmitter node of thelower order path and the receiver node, and setting the lower order pathvia the set higher order path and the node containing in the receivernode group.

According to the fifth aspect of the present invention, a path settingmethod in a communication network comprising:

a plurality of nodes capable to perform switching process anddemultiplexing process not only for lower order paths in a predeterminedhierarchical level among hierarchized paths but also for higher orderpaths in a hierarchical level higher than the predetermined hierarchicallevel; and

a plurality of links connecting these nodes;

the path setting method comprises:

path setting control step, responsive to a new path setting demand forsetting the lower order path, of setting the lower order path in thehigher order path when a single higher order path is set from apredetermined transmitter node group, in which a transmitter node of thelower order path belongs, to a predetermined receiver node groupincluding a receiver node.

According to the sixth aspect of the present invention, a path settingmethod in a communication system comprising:

a plurality of nodes capable to perform switching process anddemultiplexing process not only for lower order paths in a predeterminedhierarchical level among hierarchized paths but also for higher orderpaths in a hierarchical level higher than the predetermined hierarchicallevel; and

a plurality of links connecting these nodes;

the path setting method comprises:

path setting control step to be activated in responsive to a new pathsetting demand for setting the lower order path, in the path settingcontrol step, the higher order path being set between the transmitternode group consisted of nodes reachable from the transmitter node viathe higher order path and the receiver node when the single higher orderpath is not set between the transmitter node of the lower order path andthe receiver node, and the lower order path being set via the set higherorder path and the node containing in the transmitter node group.

According to the seventh aspect of the present invention, a path settingmethod in a communication system comprising:

a plurality of nodes capable to perform switching process anddemultiplexing process not only for lower order paths in a predeterminedhierarchical level among hierarchized paths but also for higher orderpaths in a hierarchical level higher than the predetermined hierarchicallevel; and

a plurality of links connecting these nodes;

the path setting method comprises:

path setting control step to be activated in responsive to a new pathsetting demand for setting the lower order path, in the path settingcontrol step, in the path setting control step, the higher order pathbeing set between the transmitter node group consisted of the nodesreachable from the transmitter node via the higher order path and thereceiver node group consisted of the nodes reachable from the receivernode when the single higher order path is not set between thetransmitter node of the lower order path and the receiver node, and thelower order path being set via the set higher order path and the nodecontaining in the transmitter node group and the receiver node group.

According to the eighth aspect of the present invention, a path settingmethod in a communication system comprising:

a plurality of nodes capable to perform switching process anddemultiplexing process not only for lower order paths in a predeterminedhierarchical level among hierarchized paths but also for higher orderpaths in a hierarchical level higher than the predetermined hierarchicallevel; and

a plurality of links connecting these nodes;

the path setting method comprises:

path setting control step to be activated in responsive to a new pathsetting demand for setting the lower order path, in the path settingcontrol step, in the path setting control step, the higher order pathbeing set between the transmitter node and the receiver node groupconsisted of the nodes reachable from the receiver node when the singlehigher order path is not set between the transmitter node of the lowerorder path and the receiver node, and the lower order path being set viathe set higher order path and the node containing in the receiver nodegroup.

According to the ninth aspect of the present invention, a nodecomprises:

a switch for switching not only lower order paths in a predeterminedhierarchical level among hierarchized paths but also higher order pathsin a hierarchical level higher than the predetermined hierarchicallevel;

multiplexing means for multiplexing a plurality of the lower order pathsin the higher order path;

demultiplexing means for demultiplexing the higher order path into thelower order paths; and

path setting control means responsive to a new path setting demand forsetting the lower order path containing own node as a transmitter node,for setting the lower order path in the higher order path when a singlehigher order path is set from a predetermined transmitter node group, inwhich a transmitter node of the lower order path belongs, to apredetermined receiver node group including a receiver node.

According to the tenth aspect of the present invention, a nodecomprises:

a switch for switching not only lower order paths in a predeterminedhierarchical level among hierarchized paths but also higher order pathsin a hierarchical level higher than the predetermined hierarchicallevel;

multiplexing means for multiplexing a plurality of the lower order pathsin the higher order path;

demultiplexing means for demultiplexing the higher order path into thelower order paths; and

path setting control means responsive to a new path setting demand forsetting the lower order path, the path setting control means setting thehigher order path between the transmitter node group consisted of nodesreachable from the transmitter node via the higher order path and thereceiver node when the single higher order path is not set between thetransmitter node of the lower order path and the receiver node, andsetting the lower order path via the set higher order path and the nodecontaining in the transmitter node group.

According to the eleventh aspect of the present invention, a nodecomprises:

a switch for switching not only lower order paths in a predeterminedhierarchical level among hierarchized paths but also higher order pathsin a hierarchical level higher than the predetermined hierarchicallevel;

multiplexing means for multiplexing a plurality of the lower order pathsin the higher order path;

demultiplexing means for demultiplexing the higher order path into thelower order paths; and

path setting control means responsive to a new path setting demand forsetting the lower order path, the path setting control means setting thehigher order path between the transmitter node group consisted of thenodes reachable from the transmitter node via the higher order path andthe receiver node group consisted of the nodes reachable from thereceiver node when the single higher order path is not set between thetransmitter node of the lower order path and the receiver node, andsetting the lower order path via the set higher order path and the nodecontaining in the transmitter node group and the receiver node group.

According to the twelfth aspect of the present invention, a nodecomprises:

a switch for switching not only lower order paths in a predeterminedhierarchical level among hierarchized paths but also higher order pathsin a hierarchical level higher than the predetermined hierarchicallevel;

multiplexing means for multiplexing a plurality of the lower order pathsin the higher order path;

demultiplexing means for demultiplexing the higher order path into thelower order paths; and

path setting control means responsive to a new path setting demand forsetting the lower order path, the path setting control means setting thehigher order path between the transmitter node and the receiver nodegroup consisted of the nodes reachable from the receiver node when thesingle higher order path is not set between the transmitter node of thelower order path and the receiver node, and setting the lower order pathvia the set higher order path and the node containing in the receivernode group.

According to the thirteenth aspect of the present invention, a networkmanagement system in a communication network including a plurality ofnodes capable to perform switching process and demultiplexing processnot only for lower order paths in a predetermined hierarchical levelamong hierarchized paths but also for higher order paths in ahierarchical level higher than the predetermined hierarchical level, anda plurality of links connecting these nodes;

the network management system comprises:

path setting control means responsive to a new path setting demand forsetting the lower order path, for setting the lower order path in thehigher order path when a single higher order path is set from apredetermined transmitter node group, in which a transmitter node of thelower order path belongs, to a predetermined receiver node groupincluding a receiver node.

According to the fourteenth aspect of the present invention, a networkmanagement system in a communication network including a plurality ofnodes capable to perform switching process and demultiplexing processnot only for lower order paths in a predetermined hierarchical levelamong hierarchized paths but also for higher order paths in ahierarchical level higher than the predetermined hierarchical level, anda plurality of links connecting these nodes;

the network management system comprises:

path setting control means responsive to a new path setting demand forsetting the lower order path, the path setting control means setting thehigher order path between the transmitter node group consisted of nodesreachable from the transmitter node via the higher order path and thereceiver node when the single higher order path is not set between thetransmitter node of the lower order path and the receiver node, andsetting the lower order path via the set higher order path and the nodecontaining in the transmitter node group.

According to the fifteenth aspect of the present invention, a networkmanagement system in a communication network including a plurality ofnodes capable to perform switching process and demultiplexing processnot only for lower order paths in a predetermined hierarchical levelamong hierarchized paths but also for higher order paths in ahierarchical level higher than the predetermined hierarchical level, anda plurality of links connecting these nodes;

the network management system comprises:

path setting control means responsive to a new path setting demand forsetting the lower order path, the path setting control means setting thehigher order path between the transmitter node group consisted of thenodes reachable from the transmitter node via the higher order path andthe receiver node group consisted of the nodes reachable from thereceiver node when the single higher order path is not set between thetransmitter node of the lower order path and the receiver node, andsetting the lower order path via the set higher order path and the nodecontaining in the transmitter node group and the receiver node group.

According to the sixteenth aspect of the present invention, a networkmanagement system in a communication network including a plurality ofnodes capable to perform switching process and demultiplexing processnot only for lower order paths in a predetermined hierarchical levelamong hierarchized paths but also for higher order paths in ahierarchical level higher than the predetermined hierarchical level, anda plurality of links connecting these nodes;

the network management system comprises:

path setting control means responsive to a new path setting demand forsetting the lower order path, the path setting control means setting thehigher order path between the transmitter node and the receiver nodegroup consisted of the nodes reachable from the receiver node when thesingle higher order path is not set between the transmitter node of thelower order path and the receiver node, and setting the lower order pathvia the set higher order path and the node containing in the receivernode group.

According to the seventeenth aspect of the present invention, a storagemedium storing a program to be executed by a computer for path settingcontrol in a communication network comprising:

a plurality of nodes capable to perform switching process anddemultiplexing process not only for lower order paths in a predeterminedhierarchical level among hierarchized paths but also for higher orderpaths in a hierarchical level higher than the predetermined hierarchicallevel; and

a plurality of links connecting these nodes;

the program comprises:

path setting control step, responsive to a new path setting demand forsetting the lower order path, of setting the lower order path in thehigher order path when a single higher order path is set from apredetermined transmitter node group, in which a transmitter node of thelower order path belongs, to a predetermined receiver node groupincluding a receiver node.

According to the eighteenth aspect of the present invention, a storagemedium storing a program to be executed by a computer for path settingcontrol in a communication network comprising:

a plurality of nodes capable to perform switching process anddemultiplexing process not only for lower order paths in a predeterminedhierarchical level among hierarchized paths but also for higher orderpaths in a hierarchical level higher than the predetermined hierarchicallevel; and

a plurality of links connecting these nodes;

the program comprises:

path setting control step to be activated in responsive to a new pathsetting demand for setting the lower order path, in the path settingcontrol step, the higher order path being set between the transmitternode group consisted of nodes reachable from the transmitter node viathe higher order path and the receiver node when the single higher orderpath is not set between the transmitter node of the lower order path andthe receiver node, and the lower order path being set via the set higherorder path and the node containing in the transmitter node group.

According to the nineteenth aspect of the present invention, a storagemedium storing a program to be executed by a computer for path settingcontrol in a communication network comprising:

a plurality of nodes capable to perform switching process anddemultiplexing process not only for lower order paths in a predeterminedhierarchical level among hierarchized paths but also for higher orderpaths in a hierarchical level higher than the predetermined hierarchicallevel; and

a plurality of links connecting these nodes;

the program comprises:

path setting control step to be activated in responsive to a new pathsetting demand for setting the lower order path, in the path settingcontrol step, in the path setting control step, the higher order pathbeing set between the transmitter node group consisted of the nodesreachable from the transmitter node via the higher order path and thereceiver node group consisted of the nodes reachable from the receivernode when the single higher order path is not set between thetransmitter node of the lower order path and the receiver node, and thelower order path being set via the set higher order path and the nodecontaining in the transmitter node group and the receiver node group.

According to the twentieth aspect of the present invention, a storagemedium storing a program to be executed by a computer for path settingcontrol in a communication network comprising:

a plurality of nodes capable to perform switching process anddemultiplexing process not only for lower order paths in a predeterminedhierarchical level among hierarchized paths but also for higher orderpaths in a hierarchical level higher than the predetermined hierarchicallevel; and

a plurality of links connecting these nodes;

the program comprises:

path setting control step to be activated in responsive to a new pathsetting demand for setting the lower order path, in the path settingcontrol step, in the path setting control step, the higher order pathbeing set between the transmitter node and the receiver node groupconsisted of the nodes reachable from the receiver node when the singlehigher order path is not set between the transmitter node of the lowerorder path and the receiver node, and the lower order path being set viathe set higher order path and the node containing in the receiver nodegroup.

According to the twenty-first aspect of the present invention, acommunication network comprises:

a plurality of nodes capable to perform switching process anddemultiplexing process not only for lower order paths in a predeterminedhierarchical level among hierarchized paths but also for higher orderpaths in a hierarchical level higher than the predetermined hierarchicallevel;

a plurality of links connecting these nodes;

a group being preliminarily established within a predetermined value ofhop numbers from each of the plurality of nodes;

setting information of the higher order path being stored in the eachnode; and

the setting information being exchanged within the group for making thesetting information stored in respective nodes in the group consistentwith each other in the group.

In summary, a first path setting system according to the presentinvention checks whether the higher order path is set from the groupformed by the transmitter node to the group formed by the receiver nodewhen the new lower order path is to be set. When the higher order pathis already set, the new lower order path is set in the higher orderpath. By this, lower order paths established in the group is aggregatedto the higher order path to effectively use the vacant bands in thehigher order path.

In a second path setting system according to the present invention, whenthe lower order path is newly set, the higher order path is newly setbetween the group consisted of nodes, to which the transmitter node canreach via the higher order path and the group consisted of nodes, towhich the receiver node can reach via the higher order path. The lowerorder path is set via the node in the group and the newly set higherorder path. Thus, since the already set higher order path from thetransmitter node is effectively used, the vacant band in the higherorder path can be effectively used.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be understood more fully from the detaileddescription given hereinafter and from the accompanying drawings of thepreferred embodiment of the present invention, which, however, shouldnot be taken to be limitative to the invention, but are for explanationand understanding only.

In the drawings:

FIG. 1 is a block diagram showing a construction of the first embodimentof distributingly controlled network according to the present invention;

FIG. 2 is a block diagram showing an internal construction of a nodedevice in the first embodiment of the present invention;

FIG. 3 is a block diagram showing information exchanged between nodesand information stored in a database employed in the first embodiment;

FIGS. 4A and 4B are flowcharts for setting hierarchized path in thefirst and second embodiments of the present invention;

FIG. 5 is a block diagram showing a condition of path set in the firstand second embodiments of the present invention;

FIG. 6 is a block diagram showing exchanging of accessible informationand a procedure;

FIG. 7 is a flowchart for setting hierarchized path in the thirdembodiment of the present invention;

FIG. 8 is a block diagram showing a condition of path set in the thirdembodiment of the present invention;

FIG. 9 is a flowchart for setting hierarchized path in the fourthembodiment of the present invention;

FIG. 10 is a block diagram showing a condition of path set in the fourthembodiment of the present invention;

FIG. 11 is a block diagram showing a construction of the networkconcentrically controlled by an NMS; and

FIG. 12 is a block diagram showing a construction of the network dividedinto sub-networks.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention will be discussed hereinafter in detail in termsof the preferred embodiments of the present invention with reference tothe accompanying drawings. In the following description, numerousspecific details are set forth in order to provide a thoroughunderstanding of the present invention.

FIGS. 1 and 2 are block diagrams showing a network construction and anode in the first embodiment of the present invention. In FIG. 1, acommunication network according to the present invention includesoptical network devices (hereinafter referred to as node) 10-1 to 10-16.Each of these nodes has a construction shown in FIG. 2 and has afunction for switching both of a wavelength path and a waveband path ashierarchized path. Each node also has a function for multiplexingwavelength paths into waveband path and demultiplexing the waveband pathinto wavelength paths. Wavelength links 11 and wavelength group links 12are constructed with a plurality of optical fibers.

In FIG. 2, each of the nodes 10-1 to 10-16 includes a wavelength groupcross connect device 20, a wavelength cross connect device 21, a database 22, a control portion 23 controlling the wavelength group crossconnect device 20 and the wavelength cross connect device 21,demultiplexers 24 and multiplexers 25 for waveband paths, demultiplexers26 and multiplexers 27 for waveband paths, demultiplexers 28 convertingthe waveband path into wavelength paths and multiplexers 29 convertingthe wavelength paths into waveband path.

Each node is connected with adjacent node with the wavelength links 11,the wavelength group links 12 and a control channel 31 exchanging acontrol signal. On the other hand, the node is connected to not shownclient devices through links 30.

Hereinafter, the embodiments of the present invention will be discussedin connection with the network having construction set forth above interms of the case where aggregate of wavelengths N into one wavelengthgroup. FIGS. 4A, 4B and 5 are flowchart and block diagram showing thefirst embodiment of the present invention. The first embodiment of thepresent invention is a system setting the wavelength paths in thewaveband paths set between a transmitter node group consisted of thenodes located within H (H is one of natural numbers) hops from atransmitter node and a receiver node group consisted of the nodeslocated within H hops from a receiver node. Here, the nodes within Hhops represents the nodes to be reached via less than or equal to H ofphysically connected links.

At first, discussion will be given hereinafter with respect to a pathsetting information exchanging system within a group formed by thetransmitter node and the receiver node, In the first embodiment of thepresent invention, each node 10-1 to 10-16 form a group consisted ofrespective nodes physically connected to own node and located adjacent Hhops of distance from the own node. In the present invention, a group ofthe transmitter node will be referred to as the transmitter node groupand a group of the receiver node will be referred to as the receivernode group. For example, when the nodes located within adjacent one hop(H−1) are assumed to form a group, groups of the nodes 10-5 and 10-15are respectively consisted of the nodes 10-2, 10-3, 10-6 and 10-11,10-12, 10-16, as shown in FIG. 1. On the other hand, in differentviewpoint, the node 10-5 belongs in a group of the node 10-2, a group ofthe node 10-3, and a group of the node 10-6. The node 10-15 belongs in agroup of the node 10-11, a group of the node 10-12, and a group of thenode 10-16.

Each node has to store path setting information relating to the wavebandpaths already set by the nodes contained in the group of the own node,in a database 22. This path setting information includes an ID(identification information) of a transmitter node, ID of a receivernode of the waveband path already set by own node, and a vacantinformation of the waveband path and is exchanged by distributing thewaveband path setting information, in which the ID of the transmitternode is the ID of own node, to respective nodes in the own group throughthe control channel 31. For example, when the node 10-2 contained in thegroup of the node 10-5 sets the waveband path to the nodes 10-7, 10-12and 10-14, the node 10-2 stores the path setting information shown onleft side in FIG. 3, in own database 22. Among information of thedatabase 22, the waveband path information, in which the ID of thetransmitter node is the ID of own node (node 10-2) is transmitted eachnode (including the node 10-5) belonging in the group of the own node.Each node (including the node 10-5) receiving the waveband path settinginformation of the node 10-2 updates the own database 22. Bytransmitting the wavelength group setting information, in which thetransmitter node ID is the ID of the own node, among information storedin the own database 22 in similar manner from all of other nodes (node10-3, node 10-6) contained within the group of the node 10-5, to thenodes belonging in respective groups of their own nodes, the pathsetting information can be exchanged between all of nodes belonging inthe group of the node 10-5. Thus, the database of the node 10-5 maystore the waveband path setting information, in which each nodecontained in the group of the node 10-5 becomes the transmitter node asshown in the right side in FIG. 3.

The path setting information is distributed regularly or at everyoccasion of setting new path using a routing function, such as OSPF(Open Shortest Path Fast) or so forth, or a signaling function. When therouting function is used, a value “H” corresponding to number of hops,is set in a live field of each packet carrying the path settinginformation. The value of the live field is decremented by “1” at everyone hop of transmission to transmit the packet to the adjacent nodeuntil the value of the live field becomes “0.” The node receiving thepacket having the live filed “0” disposes the packet By repeating theforegoing procedure, the path setting information can be distributed toall of the nodes in the own group.

On the other hand, when the signaling function is used, since each nodeis preliminarily known a topology information of the network, the nodetransmitting the path setting information performs distribution of thepath setting information by transmitting the path setting information tothe nodes belonging in the own group.

Next, a path setting procedure in the case where a wavelength pathsetting demand for setting the wavelength path from the node 10-5 to thenode 10-15 occurs, will be discussed using a flowchart of FIGS. 4A and4B with reference to FIG. 5. The node 10-5 receiving a path settingdemand (S40-1) from a client device or the like makes judgment whetherthe path setting demand requires establishment of the waveband path orthe wavelength path. If the path setting demand requires establishmentof the waveband path, the shortest route from the transmitter node tothe receiver node is calculated by CSPF algorithm using only link havingvacant band (S40-20) for setting the waveband path B2 along the route(S40-21).

It should be noted that the setting procedure of the path is to transmitthe path setting demand from the transmitter node to the receiver nodeper one hop. Each node receiving this demand switches the wavelengthgroup cross connect device 20 of the own node. When this setting demandarrives the receiver node, a response signal is transmitted from thereceiver node to the transmitter node per one hop to verify whether thewavelength group cross connect device 20 is set correctly. Hereinafter,in the setting of the path, the foregoing operation is also applied to awavelength group cross connect device or a wavelength cross connectdevice.

When the demand is for wavelength path, retrieval is performed againstthe database 22 for checking whether the path can be reached to thereceiver node through one waveband path already set from the transmitternode to the receiver node (S40-3). When one waveband path B 2 is alreadyset (S40-4) and if a vacant band for setting the wavelength path ispresent in the waveband path B2 (S40-14), a route of the wavelengthpaths in the set waveband path B2 and the shortest route (route havingphysically the shortest length) from the transmitter node to thereceiver node calculated by the CSPF algorithm using only links havingvacant bands are compared (S40-15). Comparing condition formula is“true” (S40-16), a wavelength path W2 in the waveband path B2 is set(S40-19). As the comparing condition formula, there is formula expressedby hop number of the retrieved route≦hop number of the shortest route+(Kis arbitrary natural number) or so forth.

At step S40-4, the waveband path is not set, or at step S40-16, thecomparing condition formula is “false,” retrieval is performed againstthe database for checking whether the waveband path is set between thetransmitter node group and the receiver node group (S40-5). If thewaveband path set forth above is not connected between the groups, theshortest route from the transmitter node to the receiver node iscalculated using only links having vacant bands by the CSPF algorithm(S40-17)(calculation can be eliminated when the shortest route isalready calculated at step S40-15 and the route information is stored)to set a single waveband path B2 along the shortest route (S40-18) andset a wavelength path W2 in the single waveband path B 2 (S40-19). Here,the wavelength path can be set simultaneously with the waveband path byswitching the wavelength cross connect in conjunction with switching ofthe wavelength group cross connect at each node.

At step S40-6, if the waveband path (B1 of FIG. 5) between the groups isset, the waveband path, in which the route of the wavelength pathsconnecting the transmitter node and the receiver node becomes theshortest as a result of routing through the waveband path (S40-7), isretrieved. Then, check is performed against the database 22 whetherthere is a vacant band to set the wavelength path in the retrievedwaveband path (S40-8). If the vacant band is not available, the wavebandpath is eliminated from retrieving object (S40-9), the process returnsto step S40-6. As a result of retrieval at step S40-8, when the band isvacant, the shortest route from the transmitter node to the receivernode calculated using only links having vacant bands by the CSPFalgorithm and the retrieved route are compared under the comparingcondition formula (S40-11). If the comparing condition formula is“false,” the process is advanced to step S40-15, and if the comparingcondition formula is “true,” the wavelength path W1 is set in thewaveband path (S40-13). As the comparing condition formula, there isformula expressed by hop number of the retrieved route≧hop number of theshortest route+(K is arbitrary natural number) or so forth.

As set forth above, after setting the wavelength path or the wavebandpath (S40-12, S40-18, S40-19, S40-21), the nodes at respective endpoints of the waveband path and the wavelength path add the path settinginformation in the database 22 and transmit the updated path settinginformation to each node in the group using the foregoing path settinginformation exchanging procedure (S40-13). The node receiving the pathsetting information updates information in the database 22.

By repeatedly performing the path setting method set forth above betweenthe transmitter node and the receiver node to be set, the wavelengthpath can be efficiently aggregated without dividing the network intosub-networks. On the other hand, in the shown embodiment, since eachnode is not required to know the path setting information of the overallnetwork, a traffic amount for transmitting the path setting informationto each node can be reduced.

As the second embodiment of the present invention, discussion will begiven for the case where each node stores the node information which canbe reached via the waveband path with reference to FIG. 5. Pointsdifferent from the first embodiment of the present invention, iscapability of setting of the wavelength paths via the waveband pathsbetween groups by knowing information of nodes which the nodes in thegroup can be reached through the waveband path (reachable nodeinformation).

At first, discussion will be given for exchanging system of thereachable node information for exchanging node informationrepresentative of nodes which can be reached by each node through thewaveband path. The reachable node information is updated regularly or atevery occurrence of setting of new path using the routing function. Eachnode distributes the setting information of the waveband path set by ownnode to all end point nodes set the waveband paths from the own node.The node receiving the path setting information adds the receivedinformation to the database 22 of own node, adds the path settinginformation of the waveband paths set by the own node to the receivedinformation to distribute the information to the all of the end pointnodes to which the own node set the waveband paths. By repeating theforegoing operation, each node can obtain the node information reachablethrough a plurality of waveband paths.

For example, in FIG. 5, when the nodes 10-3 and 10-10, and the nodes10-10 and 10-16 are respectively connected by two waveband paths B3 andB4, process of exchanging the information starting from the node 10-16is shown in FIG. 6. In FIG. 6, the node 10-16 transmits the already setwaveband path information 16-D1 to the node 10-10, to which the own nodesets the waveband path. The node 10-10 receiving this information addsthe received information time identifier the database of the own node,and in conjunction therewith, transmits information 10-D1 to the nodes10-3 and 10-16 to which the waveband paths are set. The node 10-3receiving the information 10-D1 updates the database of own node totransmit information 3-D1 to the node 10-10. This operation is repeateduntil information in respective nodes becomes consistent with eachother. As a result of exchanging of the reachable node information, itcan be appreciated that the node 10-3 can reach the node 10-16 via thenode 10-10. The reachable node information shown in FIG. 6 thus obtainedis transmitted to other nodes from the node 10-3 in the transmitter nodegroup in the foregoing procedure. On the other hand, the reachable nodeinformation is transmitted to other nodes in the receiver node groupfrom the node 10-16.

Next, path setting method will be discussed for the case where each nodestores the reachable node information in the database 22. While the pathsetting method is similar to that in the first embodiment of the presentinvention, it can be appreciated that the transmitter node 10-5 canreach the receiver node group via the node 10-10 from the transmitternode group by exchanging the path setting information within the group.As a result, at step S40-5 of FIG. 4, a route via a plurality ofwaveband paths is added to a list of the routes reachable to thereceiver node group through a plurality of waveband paths. Subsequently,according to the procedure up to step S40-11, the route through aplurality of (two) waveband paths B3 and B4. Then, the wavelength W3 isset via the node 10-10.

Accordingly, even when the groups are connected via a plurality ofwaveband paths, the wavelength path can be set in the waveband path. Incomparison with the first embodiment, the waveband path can be used moreefficiently for setting the wavelength paths. Furthermore, the fixedsub-network can be regarded as group of each node. The first and secondembodiments of the present invention is applicable even for theconstruction, in which the network disclosed in the prior art is dividedinto the sub-networks. In this case, the path information is exchangedbetween the nodes contained in each sub-network. The point differentfrom the prior art is not to fixed the node to process the wavelengthpath to permit each node to process both of the higher order path andthe lower order path. On the other hand, in the shown embodiment, sinceeach node is not required to know the path setting information of theoverall network, a traffic amount for transmitting the path settinginformation to each node can be reduced.

FIGS. 7 and 8 are flowchart and block diagram showing the thirdembodiment of the present invention. The third embodiment of the presentinvention is a system for setting the wavelength path via the nodecontained in the transmitter node group by setting the waveband pathbetween the transmitter node group consisted of nodes reachable from thetransmitter node through the waveband path and the receiver node.

At first, each node forms the group consisted of nodes reachable fromthe own node via the waveband paths. For example, as shown by the areaencircled by one-dotted line in FIG. 8, when the waveband path is setfrom the node 10-5, the group information stored in the database 22 ofthe node 10-5 is information relating to the nodes 10-1, 10-2, 10-3,10-4, 10-8, 10-10 and 10-12. The reachable node information is obtainedby exchanging the reachable information described in the secondembodiment.

Next, operation will be discussed for the case where the path settingdemand for setting demand from the node 10-5 to the node 10-15 occursusing FIG. 7 with reference to FIG. 8. In FIG. 7, up to the processes ofA and B, processes are performed through the same process as those inthe first embodiment of the flowchart of FIG. 4. After the process or Aor B, the shortest route from the each node (10-1, 10-2, 10-3, 10-4,10-8, 10-10, 10-12) contained in the transmitter node group to thereceiver node 10-15 is calculated using only links having vacant band bythe CSPF algorithm (S41-1).

Then, a route which has minimum sum of hop number of the route derivedat step S41-1 and routes to the nodes (10-1, 10-2, 10-3, 10-4, 10-8,10-10, 10-12) in the group, namely a route of minimum hop number of theroute from the transmitter node to the receiver node via the nodes inthe transmitter node group, is selected (S41-2). When no vacant band forsetting the wavelength path is present in the waveband path of the route(S41-3), the processes of S41-2 are repeated eliminating the routehaving no vacant band for setting the wavelength path from selectionobject.

At step S41-3, if the vacant band is present, the route is compared withthe shortest route from the transmitter node to the receiver node. Ifthe comparing condition formula is “false” (S41-6), a process of C isperformed. If the comparing condition formula is “true,” the wavebandpath B8 from the node 10-12 of the transmitter node group to thereceiver node is set (S41-7) , and then the wavelength path W1 is setfrom the transmitter node to the receiver node via the waveband pathsB3, B5 and B8. Subsequently, the process is moved to a process D.

By repeating the foregoing path setting method between the nodes of thetransmitter node and the receiver node to set, the wavelength path canbe efficiently aggregated without dividing the network into the sub-networks. Thus, bands in the waveband path can be used effectively. On theother hand, in the shown embodiment, using the setting information ofthe waveband path set from the transmitter node and the wavelength pathgroup set from the receiver node, the transmitter node sets the route.Therefore, more optimal route is selected in comparison with otherembodiments.

FIGS. 9 and 10 are flowchart and the block diagram showing the fourthembodiment of the present invention. The fourth embodiment is a systemfor setting the wavelength path via the node in the transmitter nodegroup and the node in the receiver node group by setting the wavebandpath between the transmitter node group consisted of the nodes reachablefrom the transmitter node and the receiver node group consisted of thenodes reachable from the receiver node.

Different from the third embodiment, in the fourth embodiment,specifying node included in the receiver node group, the transmitternode is required to know the setting information of the waveband path ofthe overall network. Exchanging of the waveband path setting informationmay be performed using the system similar to exchanging of the reachablenode information discussed in connection with the second embodiment ofthe present invention. A point where the exchanging system of thewaveband path setting information of the overall network is differentfrom the exchanging system of the reachable node information of thesecond embodiment, is that the path setting information is notdistributed to the node to which the waveband path is set, but isdistributed to all adjacent nodes connected by the optical fiber. Bythis, each node can obtain the setting information of the waveband pathsof the overall network. This information may be updated regularly or atevery occurrence of setting of new path using the routing function.

At first, each node forms a group consisted of the nodes reachable fromthe own node via the waveband path. For example, when the waveband pathsfrom each of own node is set in a condition shown in FIG. 10 except forthe waveband paths B7 and B9, the group of the node 10-5 is consisted ofnodes 10-1, 10-2, 10-3, 10-4, 10-6, 10-8 and 10-10 and the group of thenode 10-15 is consisted of the nodes 10-12, 10-13, 10-14 and 10-16. Thisinformation is stored in the database 22 of each node. The reachablenode information is obtained by the method discussed in connection withthe second embodiment set forth above. Namely, the reachable nodeinformation can be obtained by the method sequentially sending thereachable node information to the nodes connected to the own nodethrough the links.

Next, discussion will be given for operation in the case where a pathsetting demand for setting path from the node 10-5 to the node 10-15occurs, using FIG. 9 with reference to FIG. 10. In FIG. 9, up to theprocesses of A and B, processes are performed through the same processas those in the first embodiment of the flowchart of FIG. 4. After theprocess or A or B, the transmitter node forms the receiver node group onthe basis of the waveband path information of the overall network of thedatabase 22 (step S42-0). Next, calculation of the shortest routes fromeach node (10-1, 10-2, 10-3, 10-4, 10-6, 10-8, 10-10) contained in thetransmitter node group to each node (10-12, 10-13, 10-14, 10-16)contained in the receiver node group is performed using only linkshaving vacant bands by CSPF algorithm (S42-1).

Next, selection is made for a route, in which the sum of the calculatedroute, the route to the node in the transmitter node group and the routeto the node in the receiver node group, is minimum (here, the routethrough the nodes 10-16, 10-8 and 10-12) (S42-2). When no vacant bandfor setting the wavelength is not available in the waveband path of thisroute (S42-3), the process of step 42-2 is repeated with excluding suchroute (having no vacant band) from selection object (S42-4). At stepS42-3, if the vacant band is available, the route and the shortest routefrom the transmitter node to the receiver node are compared (S42-5). Ifthe comparing condition formula is “false” (S42-6), a process of C isperformed. If the comparing condition formula is “true,” the wavebandpath B9 from the node of the transmitter node group to the node of thereceiver node is set (S42-7) , and then the wavelength path W1 is setfrom the transmitter node to the receiver node via the waveband paths(B4, B6, B9 and B11). Subsequently, the process is moved to a process D.

By repeating the foregoing path setting method between the transmitternode and the receiver node for setting the path, the wavelength path canbe efficiently aggregated without dividing the network into the sub-networks. Thus, bands in the waveband path can be used effectively.

It should be noted that the shown embodiment is applicable when thewaveband path from the transmitter node to the receiver node groupconsisted of the reachable nodes is set and the wavelength path is setvia the waveband path.

Although the present invention has been illustrated and described withrespect to exemplary embodiment thereof, it should be understood bythose skilled in the art that the foregoing and various other changes,omission and additions may be made therein and thereto, withoutdeparting from the spirit and scope of the present invention. Therefore,the present invention should not be understood as limited to thespecific embodiment set out above but to include all possibleembodiments which can be embodied within a scope encompassed andequivalent thereof with respect to the feature set out in the appendedclaims.

For instance, while the foregoing embodiments have been discussed inconnection with the network consisted of the waveband paths and thewavelength paths, the invention is likewise applicable for the networksconsisted of other higher order paths and lower order paths. Also, thepresent invention is applicable for the network having paths havingthree or more different granularities. Namely, the present invention isapplicable for any networks having hierarchized paths depending uponlarge and small of bands.

On the other hand, in the foregoing embodiments, discussion has beengiven in connection with the distributed control system setting thecontrol channels between the nodes by the nodes receiving the pathsetting demand. However, these system is applicable for concentratedcontrol system setting the nodes via a control link 2 by a networkmanagement system (NMS) 1 shown in FIG. 11. In case of the concentratedcontrol system, each node is not required to exchange the settinginformation with the other nodes and the path setting information istransmitted to the network management system 1 via the control link 2.Accordingly, since the network management system can obtain the pathsetting information of the overall path, the path can be set in thesimilar procedure as the foregoing embodiment when path setting demandis present.

Furthermore, while the foregoing embodiment is not limited to thenetwork, in which the wavelength group links and the wavelength linksare formed with different fibers as shown in FIG. 1, the presentinvention is applicable even in the network setting the waveband pathsand the wavelength paths using different bands in the same fibers. Onthe other hand, each operations of FIGS. 4, 7 and 9 are preliminarilystored in the storage medium as programs to load on the computerinstalled in the node device for execution.

With the invention set forth above, since the lower order paths can bemultiplexed in the higher order paths efficiently, the network resourcecan be used effectively even in the network, in which large number oflower order path setting demands can occur. On the other hand, accordingto the present invention, since the higher order path can be establishedby aggregating lower order paths at the arbitrary node. Therefore, it isnot required to divide the network into sub-networks. By this, even whenfailure is caused in the node setting the higher order path, significantinfluence on the network can be avoided.

1. A communication network comprising: a plurality of nodes capable toperform switching process and demultiplexing process not only forpredetermined order paths in a predetermined hierarchical level(hereinafter referred to lower order path) among hierarchized paths butalso for higher order paths in a hierarchical level higher than saidpredetermined hierarchical level; a plurality of links connecting thesenodes; and path setting control means responsive to a new path settingdemand for setting the lower order path, said path setting control meanssetting the higher order path between said transmitter node groupconsisted of the nodes reachable from said transmitter node via saidhigher order path and said receiver node group consisted of the nodesreachable from said receiver node when the single higher order path isnot set between said transmitter node of said lower order path and thereceiver node, and setting said lower order path via the set higherorder path and the node containing in said transmitter node group andsaid receiver node group.
 2. A path setting method in a communicationsystem comprising: a plurality of nodes capable to perform switchingprocess and demultiplexing process not only for predetermined orderpaths in a predetermined hierarchical level (hereinafter referred tolower order path) among hierarchized paths but also for higher orderpaths in a hierarchical level higher than said predeterminedhierarchical level; and a plurality of links connecting these nodes;said path setting method comprising: path setting control step to beactivated in responsive to a new path setting demand for setting thelower order path, in said path setting control step, step, the higherorder path being set between said transmitter node group consisted ofthe nodes reachable from said transmitter node via said higher orderpath and said receiver node group consisted of the nodes reachable fromsaid receiver node when the single higher order path is not set betweensaid transmitter node of said lower order path and the receiver node,and said lower order path being set via the set higher order path andthe node containing in said transmitter node group and said receivernode group.
 3. A path setting method as set forth in claim 2, wherein insaid path setting control step, a database is provided for storingreachable path information indicative of a route through which each nodebelonging in said transmitter node group is reachable to said receivernode group or said receiver node via the higher order path, and pathsetting control is performed with reference to the information in saiddatabase.
 4. A node comprising: a switch for switching not onlypredetermined order paths in a predetermined hierarchical level(hereinafter referred to lower order path) among hierarchized paths butalso higher order paths in a hierarchical level higher than saidpredetermined hierarchical level; multiplexing means for multiplexing aplurality of said lower order paths in said higher order path;demultiplexing means for demultiplexing said higher order path into saidlower order paths; and path setting control means responsive to a newpath setting demand for setting the lower order path, said path settingcontrol means setting the higher order path between said transmitternode group consisted of the nodes reachable from said transmitter nodevia said higher order path and said receiver node group consisted of thenodes reachable from said receiver node when the single higher orderpath is not set between said transmitter node of said lower order pathand the receiver node, and setting said lower order path via the sethigher order path and the node containing in said transmitter node groupand said receiver node group.
 5. A network management system in acommunication network including a plurality of nodes capable to performswitching process and demultiplexing process not only for predeterminedorder paths in a predetermined hierarchical level (hereinafter referredto lower order path) among hierarchized paths but also for higher orderpaths in a hierarchical level higher than said predeterminedhierarchical level, and a plurality of links connecting these nodes;said network management system comprising: path setting control meansresponsive to a new path setting demand for setting the lower orderpath, said path setting control means setting the higher order pathbetween said transmitter node group consisted of the nodes reachablefrom said transmitter node via said higher order path and said receivernode group consisted of the nodes reachable from said receiver node whenthe single higher order path is not set between said transmitter node ofsaid lower order path and the receiver node, and setting said lowerorder path via the set higher order path and the node containing in saidtransmitter node group and said receiver node group.
 6. A networkmanagement system as set forth in claim 5, wherein said path settingcontrol means has a database storing reachable path informationindicative of a route through which each node belonging in saidtransmitter node group is reachable to said receiver node group or saidreceiver node via the higher order path, and performs path settingcontrol with reference to the information in said database.
 7. A storagemedium storing a program to be executed by a computer for path settingcontrol in a communication network comprising: a plurality of nodescapable to perform switching process and demultiplexing process not onlyfor predetermined order paths in a predetermined hierarchical levelamong (hereinafter referred to lower order path) hierarchized paths butalso for higher order paths in a hierarchical level higher than saidpredetermined hierarchical level; and a plurality of links connectingthese nodes; said program comprising: path setting control step to beactivated in responsive to a new path setting demand for setting thelower order path, in said path setting control step, in said pathsetting control step, the higher order path being set between saidtransmitter node group consisted of the nodes reachable from saidtransmitter node via said higher order path and said receiver node groupconsisted of the nodes reachable from said receiver node when the singlehigher order path is not set between said transmitter node of said lowerorder path and the receiver node, and said lower order path being setvia the set higher order path and the node containing in saidtransmitter node group and said receiver node group.